Session G10: The Small Neutrino Mixing Angle Theta13

First Results from Double Chooz and Future Prospects

The Double Chooz experiment has begun its first phase of operation, using a single detector to search for oscillations of reactor antineutrinos at a baseline of 1050 m and measure the small mixing angle, $\theta_{13}$. A first set of data from the detector have been analyzed, with the expected antineutrino flux prediction using the measurement of the Bugey4 experiment as an anchor point. The results show an indication of reactor electron antineutrino disappearance consistent with neutrino oscillations. Future prospects for measurement with Double Chooz in a single-detector phase are discussed.   

The Daya Bay Experiment I: Introduction and Overview

The Daya Bay Reactor Neutrino Experiment aims to precisely measure $\theta_{13}$, the least well known mixing angle in the PMNS matrix. Our design sensitivity is 0.01 in $\sin^2(2\theta_{13})$, based on comparing the relative flux of antineutrinos from the reactor cores with ``identical'' antineutrino detectors at near and far distances. The detectors are immersed in water pools that provide active and passive shielding against backgrounds. This talk will introduce the importance of measuring $\theta_{13}$, give an overview of our experimental arrangement, and outline our strategies for near and long term data taking. Details are given in subsequent presentations in this session.   

Abstract of DYB APS April talk II: Design, Construction, and Calibration of the Antineutrino Detectors

The Daya Bay Reactor Neutrino Experiment aims for the cleanest and the most precise measurement of the third neutrino mixing angle $\theta_{13}$, which will unlock the gateway of studying the CP violation in leptonic sector. The principle of the central Antineutrino Detectors is the inverse beta decay with coincidence detection of positron scitillation/annilation and neutron capture on Gadolinium. A 3-zone design was adopted for Antineutrino Detectors to minimize systematic uncertainties in detector target mass. Furthermore, an automated calibration system was developed to give a comprehensive and robust energy calibration with $Ge$, $Co$ and $AmC$ sources. In this talk, we will describe the design and construction of our Antineutrino Detectors. In addition, the performance of calibrations of our Antineutrino Detectors will be presented.   

The Daya Bay Experiment III: Design, Construction, and Calibration of the Active Water Shield

The Daya Bay Experiment aims to measure the neutrino mixing angle $\theta_{13}$ precisely. In order to achieve the sensitivity of 0.01 in $\sin^2(2\theta_{13})$, muon has to be identified with the design efficiency of 99.5\%. This talk will give an overview on the Daya Bay muon system: Water Cherenkov Detector, and Resistive Plate Chambers (RPCs), its construction and calibration. Performance on real data will be discussed.   

The Daya Bay Experiment IV: Performance of Side-by-Side Antineutrino Detectors

A precise measurement of $\sin^22\theta_{13}$ is the primary goal of the Daya Bay Reactor Neutrino Experiment, which will compare the antineutrino flux in eight detectors installed at three experimental halls with different distances from the reactor cores. To minimize the impact of varying detector response on the uncertainties in the $\theta_{13}$ measurement, a large effort has gone into ensuring that detectors will be as identical as possible. In August of 2011, the Daya Bay Experiment began collecting data with its first pair of antineutrino detectors installed side-by-side in an experimental hall near the Daya Bay reactor cores. Running in this configuration, we can evaluate how identical the detectors actually are and quantify the relative detector systematic uncertainty. We will discuss antineutrino event selection in the first two detectors and show that the Daya Bay Collaboration has succeeded in building sufficiently identical detectors.   

The Daya Bay Experiment V: Overall Performance and Schedule for Neutrino Oscillation Results

The Daya Bay Reactor Neutrino Experiment aims to make a precise measurement of the least well know mixing angle of PMNS matrix, $\theta_{13}$, which is essential for future measurements of CP-violation in the lepton sector. The experiment detects anti-neutrinos from reactors at Daya Bay with eight ``identical'' Antineutrino Detectors, which distributed into three experimental halls. We started taking data from the first two Antineutrino Detectors at one of the near-sites in August 2011. The construction and commissioning of the remaining six detectors are in progress. In this talk, we present the current status of the experiment and the results of initial studies of overall performance of the operating Antineutrino Detectors in the full experimental setup. In addition, our schedule for releasing neutrino oscillation results will be presented.   

The NOvA Experiment

The NOvA experiment is designed to search for oscillations of muon neutrinos to electron neutrinos by comparing measurements of the NuMI beam composition in two detectors, a near detector at Fermilab and a far detector 810 kilometers away. These neutrino oscillations occur because the flavor eigenstates are rotated with respect to the mass eigenstates. By observing muon to electron neutrino transitions, we measure the parameter $\theta $13. Additionally, NO$\nu $A can begin to study the mass ordering and search for the effects of the CP violating phase $\delta $. NO$\nu $A is particularly well suited to the study of the mass ordering due to the large amount of earth between the neutrino source and the detector. No other planned experiment can attack this problem. In this talk, I will review the capabilities of the experiment and current status of construction.   

Status of the NOvA Near Detector Prototype

NOvA is a long-baseline neutrino experiment that is anticipating to observe oscillations of muon neutrinos into electron neutrinos. The muon neutrino source is the NuMI beam line at Fermilab. The Near and Far Detectors are built off-axis at Fermilab and northern Minnesota respectively. In order to carry out the long term goals of the experiment, the NOvA Near Detector Prototype, built on the surface at Fermilab, is currently studying aspects of the calibration and reconstruction that will impact the physics in the Near and Far Detectors. The NOVA prototype detector will run until the NuMI beam is shutdown for planned upgrades later this year. The beam muon neutrino data collected during this time will allow the study of quasi-elastic charged current interactions in the NOvA Detectors. The current status of the NOVA prototype detector and preliminary data with be shown.   

The Charged Lepton Mass Matrix and Non-zero $\theta_{13}$ with TeV Scale New Physics

We provide an explicit structure of the charged lepton mass matrix which is 2-3 symmetric except for a single breaking of this symmetry by the muon mass. We identify a flavor symmetric limit for the mass matrices where the first generation is decoupled from the other two in the charged lepton sector while in the neutrino sector the third generation is decoupled from the first two generations. The leptonic mixing in the symmetric limit can be, among other structures, the bi-maximal (BM) or the tri-bimaximal (TBM) mixing. Symmetry breaking effects are included both in the charged lepton and the neutrino sector to produce corrections to the leptonic mixing and explain the recent $\theta_{13}$ measurements. A model that extends the SM by three right handed neutrinos, an extra Higgs doublet, and two singlet scalars is introduced to generate the leptonic mixing.\\[4pt] This work was supported in part by the US-Egypt Joint Board on Scientific and Technological Co-operation award (Project ID: 1855) administered by the US Department of Agriculture, summer grant from the College of Liberal Arts, University of Mississippi and in part by the National Science Foundation under Grant No. 1068052 and 1066293 and the hospitality of the Aspen Center for Physics.